Jan Vanfleteren, an electrical engineer at the Interuniversity Micro Electronics Centre at the University of Ghent, in Belgium, has developed a new approach. It involves "thinning" an off-the-shelf microchip from 725 micrometers down to just 30 micrometers using a conventional grinding process. Vanfleteren says the process does not impair the performance of the microchip.

The chips are processed while still on the wafer from which they are cut, embedded within a thin substrate, and then connected to other components embedded within the plastic via a stretchable copper interconnect.

Vanfleteren presented a prototype flexible microcontroller at the Electronics and System Integration Technology Conference in Amsterdam last month. It can be stretched beyond 50 percent of its length (20 percent is sufficient for a biomedical device), and can be flexed 10,000 to 100,000 times before breaking. It is even machine washable, Vanfleteren notes, making it suitable for clothing.